Tony McDonald, a primary head in Warwickshire, broke down in tears and had to leave the platform recently while speaking at a public meeting about spending cuts. It was a sobering moment, and the local press and radio made much of the incident.

In truth, teachers cry much more often than people outside the profession think. When I was a head, I several times had tearful colleagues - men and women - in my room, and I once had to walk out of a fraught meeting with parents and take some moments to bring myself under control.

Talk to any head and he or she will say that tearful encounters happen from time to time. The tale of walking into the gents and finding a senior teacher sobbing with his head resting on the wall is part of the folklore of the job.

A snap identification of the causes would probably include the word “stress”. But that seems an inadequate and simplistic analysis. The stressed teachers are not necessarily the ones who cry, and the ones who cry are not always stressed.

Fifteen years ago, a super teacher who went on to build a successful career cried bitterly in my room because he had made an error which significantly set back a carefully constructed relationship with a pupil’s family. If he was clinically stressed, then so is every other teacher, and professional protestations notwithstanding, I do not think they are.

The point is, surely, that teachers, perhaps more than other professionals cannot help but get their sense of personal worth mixed up with their professional competence. The warning “don’t get personally involved” that is constantly handed down to each generation of doctors and nurses, for example, makes no sense to a teacher; teaching is, unlike the administration of medical care, an offshoot of the self.

Russell Clarke, who, as assistant general secretary of the Secondary Heads Association, spends a lot of time helping heads who have been professionally and personally bruised (sometimes literally) believes that what we are discussing is every teacher’s inner conviction that the job is about making improvements to children’s lives.

“You have to believe, in this business, that you are making things better and moving things on. If that particular spark is not there - if something happens that makes you think things are going the opposite way - it can be a very destroying occupation.”

And Dr Hilary Radnor of Exeter University, who has researched the effects on teachers of curricular change, chooses a similar metaphor, suggesting that if personal commitment is damaged, “then a light goes out, and an inner pulse stops”.

The fact that teachers do have this sense of involvement makes it difficult to lead them - at the extreme, if you tell them to change course and do something radically new, they may start to feel that their whole lives up that point have been worthless. Hence, of course, the enormous escalation in ill-health retirements, which have almost doubled since the mid-Eighties.

Hilary Radnor, in a personal research study (so far unpublished), deals with the problems that arise from trying to manage this delicate balance between a teacher’s sense of personal worth and the leader’s perceived need to move the school forward. In one section she tells of the head who, while making great play of listening to teachers, always ends up by telling them they have to do as they are told.

“Sunshine management is what the first deputy calls it (‘look sunshine, you do it or else!’) and he has had enough of it - he has resigned,” says the study.

I discovered for myself where this can end when I met a head who had moved to a school where staff for some years had been bullied, ordered around and reduced to tears. As a result they were to use the word which he constantly repeated, “damaged”.

For weeks, he did little but listen to people whose confidence had been knocked; one of them “an experienced teacher who had begun to question her ability and say that she couldn’t do the job”. Not all of the staff at this school have survived - more than one has had to be helped into retirement. “They were just too damaged” (that word again).

The lesson this head learned was that although he had to change systems and institute policies, what really mattered was the restoration of confidence and self-belief. “Getting teachers to recognise the good things they do is very difficult. Leadership is about releasing and recognising talents.”

There is a strong case for suggesting that the inner flame of confidence burns with a fragile light.

Why else, if not because they need constant reassurance, do teachers constantly talk about their work? Why is it that non-teaching partners are driven to screaming pitch by pub and dinner table conversation about classrooms and kids?

The ease with which the light can be extinguished, sometimes for good, is further illustrated by the story of the teacher - for this purpose, I shall call him Ralph - who, even now, is still suffering from painful self doubt as the result of an incident last summer.

Ralph is an experienced and successful teacher of A-level students. Last June, however, almost three weeks after the exam, the parents of all of his A-level group complained bitterly to his head, in writing, that their sons and daughters had found themselves inadequately prepared for the exam. They blamed the way the students had been taught, and were worried that their higher education prospects would be unfairly damaged.

The head replied to the parents’ letter, including some evidence from the teacher’s own records. “I was relieved that I do still keep a tight file. I could tell you everything I’ve done on any teaching day,” said Ralph.

This, however, sparked off another, much harsher, letter from the parents, reiterating the original complaints and going on to accuse the head of being patronising.

Ralph was now faced with a concerted campaign which, though deliberately directed over his head, had him - he felt - very much as its target.

Throughout, the parents insisted that they were not attacking Ralph’s professional competence; for his part, Ralph believes that if you criticise a lesson or a course, you criticise the teacher. His head felt the same way, and made this point forcibly, in writing to the parents.

Now the management ins and outs of this are interesting enough. The school was steadfastly supportive and, of course, there were fraught meetings, union involvement and so on.

What is important, though, in the context of the present discussion, was the devastating effect it all had on Ralph, not just as a teacher but as a person with a private life and a set of emotions.

As he said early on in his conversation with me: “When everyone starts saying you’re useless, then you start to believe it. I was increasingly beside myself.”

The summer holidays rapidly arrived and, suggested Ralph, “some of the others were able to cross the matter off their agenda. But for me not a day went by when I didn’t worry. I didn’t sleep properly, I was having nocturnal sweats, and I was physically sick. I couldn’t face going into the village because I thought everyone was talking about me. That whole period of my life is indescribable.”

It is important to remember here that Ralph was no insecure beginner but an experienced A-level teacher with a track record of success - which, paradoxically, is probably why the whole thing got to him as it did.

All teachers of exam groups, of course, have a surge of anxiety as results day approaches. But Ralph was on the threshold of paranoia.

“I thought there’d be a lynch mob in the car park, so I asked the head to fax the results to someone I knew, who then rang me up. The first candidate had got an ‘A’ and by that time I was in such a state that I really genuinely thought for a moment that it stood for a new category called ‘Abject failure’.”

As the list of results unfolded, it became clear there were a significant proportion of As and Bs. Every candidate had the scores he or she needed for any future plans.

But Ralph still had to be convinced. “I rang the school to confirm it. I still thought there’d be a fax from the board saying it was a horrible mistake. Only when another colleague brought the results round to my door and I’d read them three times did I start to believe them.”

What happened then? Letters of apology? Flowers? Shame-faced people at the door? (“I watched the letterbox every day.”) Now come on. Every teacher reading this knows better than that. Even after the governors wrote to the parents suggesting “that they could alleviate some of the distress by writing a note of appreciation”, Ralph says there was virtually nothing doing - certainly no concerted retraction on the level of the original complaint.

He knows, in fact, that some parents continued to feel that the good results did not invalidate their complaint or the way it was handled.

So, for Ralph, the pain goes on. “I now doubt my ability right across the board. I dread each day. I’m left with a legacy of low self-esteem. They’ve stolen a period of my life, and I feel terribly hurt by that. I look at my own kids now and I remember how I snarled at them when I shouldn’t have done. ”

Quite evidently, Ralph is in need of a rest - others have said the same. But in saying this, are we not, somehow, suggesting that he is part of the problem?

There are parallels here with the way that schools deal with bullying and the need constantly to guard against the trap of expecting the victim to carry some of the responsibility. Certainly he has refused to take time off. “I wasn’t going to be beaten and broken.”

Is Ralph at least now seeing some light ahead? To some extent he is, and sharing his story has helped. “If only I could sort my sleeping out. Last night (this was in January, remember, five months after the results came out) I woke at two, four and six, and got up feeling exhausted.”

Casting around for someone else to discuss this with, and who might provide me finally with something positive for teachers to reflect on, I thought of Heather Brooks, who for 22 years has been head of a large primary school in a very difficult area of east London.

The job, agrees Heather, has teachers always hovering between elation and despair. “You lay yourself bare. You are not thinking of protecting yourself, because that’s counterproductive - every fibre is going for the progress of the child, and that makes you vulnerable so that the slightest flick hurts so much.”

At the same time, though - and it was for this message that I went to her - that same high level of personal involvement means that there are great emotional rewards to be had.

“When I feel at my worst, I always throw everything in the corner and go back to the children and reactivate why I came into the job. They have never failed me yet. It’s hard to describe the real buzz you get from having even the tiniest involvement in a child’s progress - when a child learns to do something quite simple that he or she couldn’t do before. That’s what keeps me going. ”